Method for testing railway-traffic-controlling apparatus



June 5, 1928. 1,672,410

L. o. GRONDAHL METHOfi FOR TESTING RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Jan. 18, 1926 Agplies firakas when De-energged m ATQTORN EY Patented June 5, 1928.

UNITED STATES P IiABS O. GRONDAI-IL, OF QPITTSB URGH, AND PAUL GEIGER, OF WILKIN'SBURG, PENN- SYLVANIA, ASSIGNORS TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISS- VALE, PENNSYLVANIA, A CORPORATION OF PENN SYLVANIA.

METHOD FOR TESTING RAILWAY-TRAFFIG-COHTROLLING APPARATUS.

Application filed January 18, 1926. Serial No. 52967.

having two windings thereon, and co-oper a-ting with inductors located in the track- Way which are arranged. to vary the reluc-.

tance of the magnetic circuit through said core. l/Ve Wlll describe two forms of testing .de-

vices and one method of testing with each.

such form, allembodying our inventiomand will then point out the novel features thereof,'in claims. I i

In the accompanying drawing, Fig. 1 is a View, partly diagrammatic, illustrating one form of testing device embodying our in-. vention applied .to the train carried core of one form of railway. traflic controlling ap- V paratus. Fig. 2 is a view showinga portion of a modified form oftesting device and also embodying our invention.

Similar reference characters refer .to similar parts in both views. Y

Referring first to Fig. 1, the reference character A designates a magnetizable train carried core having two spaced pole pieces 1 and 2. This .core A is provided with two windings3 and 4, The reference character It designates a train carriediblay which is at times supplied with current from .a suitable source of energy such as a battery'5 over its own front contact- 5 in series with winding 4 and a variable resistance 7. v'llhe reference character 'V designates a magnet valve which is arranged to apply the brakes on the train when the magnet is .de-energized. Valve V is provided with a circuit including a battery 9 a front cOnt-actS ,of relay R, winding 3, and an adjustable resistance l0.

The apparatus thus far described is suitable-for use in a train control system in whichtrachway inductors .are located at intervals along the trackway. Each of these trackway inductors comprises a. co-re of magnetizable material and the pants are so disposed that as the train passes each inductor the pole pieces 1 and 2 ar'ejbridged by the core .of the inductor thereby materially re ducin the reluctance of the magnetic circuit hrough the core A. Means may also be provided for nullifyingthe effect of the trackway inductor upon the train carriedcore. For example the inductor core may be provided with a nullifying winding the terminals of which may be at times connect-- ed together. Under these conditions, that is when the circuit is closed for the winding on the trackway inductor, the effective reluctance of the inductor core is comparatively high, and the inductor will causesubstantially no change in the reluctance of the magnetic circuit through .core A on a passing train. e

As shown in the drawingrelay R is eneia gized, so that current is flowing from battery 5 through winding 4, and current is also flowing from battery 9through winding 3 I i and Valve Y,,.thereby preventing the brakes from beingapplied; The current through winding etcausesamagnetic flux in core A and the current through winding 3 causes a second flux throngh "the core. The parts are so arranged that the fluxes caused by currents in these two windings are in opposition. When the coreiA .is not over a trackway inductor the reluctance of the magnetic circuit through core A is comparatively high and the resistances 7 and 10 are so adjusted that under these conditions relay B and valve V are energized. When the train passes a ,trackway inductor which has its nullifying winding open-circuited the reluctanceof the magnetic circuit through cone A is materially decreased. The flux .due to the current winding 3 is therefore considerably increased, andas a result of this increased flux an electro-moti ve force is induced in winding 4. This induced electro-motive force causes a current to flow through relay R which current is in opposition to the current supply. by battery 5 and is of sufiicientmagnitude to cause relay R to become de-energized. Contact 8 of' relay R is therefore opened and magnet valve V becomes de energized to cause an automatic application of the brakes. The engineman can prevent this automatic application of the brakes as the train passes ,a trackway inductor by closing circuit controller K. This circuit controller is shunt- :ed around contact 6 of relay R. If the engineman operates circuit controller Ii vas the train passes an inductor the relay B may able to test the train carried apparatus without actually moving the locomotive at a definite speed past a trachway inductor, and to do this we provide a bar B of magnetizable material which is lastcned across the pole pieces 1 and2 of the core A by some suitable means such as clamps 13. The ends of bar B are separated from the pole pieces 1 and 2 by spacers 11 and 12 of non-magnetic material such as wood. The parts are so proportioned that with bar B in place the reluctance of the magnetic circuit for core A is substantially the same as the reluctance of this circuit when the core is located over a trackway inductor. The bar B is provided with a winding 15 which is connected through leads 21 with a suitable source of direct current such as a battery 16, a switch 19, an ammeter 18 and a variable resistance 17. When switch 19 is closed current from battery 16 flows through winding 15 of bar B and creates in this bar a magnetic flux which opposes the flux in the magnetic circuit resulting from the current in winding 3. By variations in the value of resistance 17 the current in winding 15 is adjusted till the resulting flux through the core A is reduced to a value corresponding to the flux traversing this core when the core is not over a trackway inductor. If now, switch 19 is opened, the sudden interruption of the current in winding 15 causes a collapse of the magnetic field due to this current. The flux from winding 3 which links winding 4 therefore increases, and the effect of this increased flux is to induce an electromotive force in winding 4: in exactly the same manner as though the actual reluctance of the magnetic circuit through core A had been increased by a trackway inductor.

Prior to using the apparatus for actual testing it is determined, by experiment or by calculation, what value of current is necessary in winding 15 to create a fluxof such magnitude that the resulting flux conditions in the core are substantially the same as those which exist when the core is not over a trackway inductor.

In actual testing, then, bar B is clamped in place as shown in Fig. 1, and switch 19 is closed. Resistance 17 is then adjusted until ammeter 18 indicates that the predetermined proper value of current is flowing in winding 15. Switch 19 is then opened. The resulting collapse of the magnetic field created by the current in winding 15 will causeavoltage to be induced in winding 1 as explained liGl'GlIlbG'fOlB. If the train carried apparatus is properly adjusted this Voltagewill cause relay R to become de-energized, and the opening of front contact 8 of this relay will de-energize magnet valve V and cause an automatic application of the brakes. If, with resistances adjusted just described, the opening of switch 19 does not cause the de-energization of relay R, the train carried apparatus is adjusted by means of resistances 10 and 7 till the opening of switch 19 causes relay R to become tie-energized.

The train carried apparatus is then reset, switch 19 is again closed, and resistance 17 is adjusted so that the current through winding 15 is somewhat less than the current through this winding for the test just described. Switch 19 istthen opened again. The parts of the train carried apparatus should be so adjusted that under these conditions the opening of switch 19 will not deenergize relay R. Theresistances 10 and 7 are so adjusted that the train carried apparatus will operate properly for the two values of current supplied to winding 15. That is, to say, the adjustment should besuch that for a value 01: current in winding 15 which simulatesthe condition of the core over a trackway inductor, the train carried apparatus will be actuated when switch 19 isopened, but that for a smaller value of current the train carried apparatus will not be actuated when this switch isopened. Assurance is thereby given that the t'raincarried apparatus will not be actuated by a trackway inductor having the circuit for its nullifying winding closed.

' For convenience the battery 16, the switch 19, the ammeter 18 and the variable resistance 17 may all be mounted in a portable unit indicated in the drawing by the broken line 22 and this unit may be connected with the winding 15 by means of long flexiblev leads 21 to permit the unit 22 to be carried to any portion of the locomotive or cab to expedite the adjustments of the train carried apparatus.

The modified form of testing apparatus shown in Fig. 2 is similar to that shown in Fig. 1 except that the battery 16 is replaced by a suitable source of alternating current such as an alternator 20. The resistance 17 may be eliminated. When switch 19 is closed the alternating electromotive force created by alternator '20 is applied to the terminals of winding 15. This electromotive force therefore causes an alternating current to flow in winding 15 and the magnitude of this current may be read on the ammeter 18. By suitable experiment it is determined what value of current will flow in winding 15 when the alternating electromotive force created by alternator 20 is supplied to the terminals of winding 15 and bar B is applied to the core A of train carried apparatus which is in normal condition. If, however, the. apparatus illustrated in Fig. 2 is applied to a core upon which one or both of the windings 3 or 4 are shortcircuited or open-circuited, the ammeter 18 will indicate a lower current or a higher current than this normal value. It :follows that by means of the apparatus illustrated in this view the train carried apparat-us may be tested for defects in the Wind ings 3 and 4.

Although we have herein shown and described only two forms of testing devices embodying our invention and only one method employing each such form also embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. The method of testing train carried traific controlling apparatus of the type comprising a magnetizable core carrying a primary winding having a circuit including a source of current, and a secondary winding having a circuit including a source of current and a relay, which apparatus co-acts with trackway inductors each having a winding included in a circuit which may be opened and closed; which method consists in reducing the reluctance of the magnetic circuit of which said core forms a part to the value obtaining when the core registers with a trackwayinductor on open circuit, creating in saidcore a counter magnetomotive force which reduces the magnetic flux in the core to the value which obtains when the core does not register with a trackway inductor, and then discontinuing said counter magnetomotive force thereby simulating the condition which obtains when the core passes over an inductor the circuit for which is open.

2. The method of testing train carried traflic controlling apparatus of the type comprising a core arranged for co-action with trackway inductors each having a winding included in a circuit which may be opened 11 and closed; which method consists in reducing the reluctance of the magnetic circuit of which said core forms a part to the value obtaining when the core registers with a trackway inductor on open circuit, creating in said core a counter magnetomotive force which reduces the magnetic flux in the core to the value which obtains when the core does not register with a trackway inductor, and then discontinuing said counter magnetomotive force thereby simulating'the condition which obtains when the core passes over an inductor the circuit for which is open.

In testimony whereof we aflix our signa- 7 tures.

LABS O. GRONDAHL. PAUL H. GEIGER. 

